CVE-2026-1638: Tenda AC21 mDMZSetCfg command injection

Vulnerability summary

CVE-2026-1638 is a high (CVSS 8.8) Injection vulnerability in tenda ac21_firmware. EPSS estimates a 2.23% chance of exploitation in the next 30 days, higher than 82.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 29-01-2026
   PublishedVulnerability first disclosed.
2. 23-02-2026
   Last modifiedVulnerability information updated.

Description

A security flaw has been discovered in Tenda AC21 1.1.1.1/1.dmzip/16.03.08.16. The impacted element is the function mDMZSetCfg of the file /goform/mDMZSetCfg. The manipulation of the argument dmzIp results in command injection. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.

• CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
• CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.